Various bone diseases including bone injury and degeneration are a growing problem worldwide. A main challenge facing bone repair and regeneration is the difficulty of constructing devices with dual structural and functional organization similar to that of natural bone tissue. Two types of structures are present in bones, cortical and trabecular. The former is generally found surrounding the latter. Cortical bone is compose of highly compacted osteons which are oriented parallel to the longitudinal axis of the bone. The channel-like structure inside osteons provides a protecting space, also known as haversian canal, for the growth of vasculature and nerves. The high tensile and mechanical strength of the structure also prevents micro-crack propagation. Surrounded by cortical bone, trabecular bone has weaker mechanical strength but features an extensive network of pores which may vary significantly.
Different technologies and devices have been developed for bone repair and regeneration. However, many of them still have serious drawbacks. Autograft, a standard approach in orthopedic surgeries, is limited by supply and donor site morbidity. Although an alternative procedure using allograft overcomes the drawbacks of autograft, it still relates to issues such as more incidences of disease transmission and higher failure rate. More recently, various scaffolds have been developed for application in bone tissue engineering. However, most of the scaffolds do not have dual structural organization as found in natural bone tissue.
A need exists for biocompatible devices which not only provide the structural similarities to natural bones but also exhibit biological affinities suitable for tissue growth.